1. Field of the Invention
The present invention relates to a valve timing adjusting device for controlling opening and closing timing of an intake valve or an exhaust valve of an internal combustion engine (hereinafter referred to as an “engine”), and to an assembly apparatus of the device.
2. Description of the Related Art
A conventional valve timing adjusting device is generally composed of a first rotor that is connected to a crankshaft of an engine by a rotational-driving force-transmitting member such as a chain, and that rotates synchronously with the crankshaft, a second rotor that is provided relatively rotatably by a predetermined angle within the first rotor, and that is integrally secured on the end face of an intake camshaft or an exhaust camshaft of the engine, and a plurality of partitioned oil pressure chambers located between the second rotor and the above first rotor. It is arranged such that an oil pump, which assumes charge of supplying oil to a sliding portion of the engine, supplies to and exhausts from these oil pressure chambers, and this hydraulic pressure controls a relative position of the second rotor with respect to the first rotor.
Among such valve timing adjusting devices, there are some valve timing adjusting devices equipped with a lock mechanism that restricts a relative rotation between the first rotor and the second rotor to an initial position in order to prevent the first rotor and the second rotor from inadvertently contacting with each other, and from thereby making abnormal noises at the time of an engine start where the device stands yet low oil pressure. This lock mechanism is generally composed of a lock hole formed in one rotor, a cylindrical receiving hole formed in the other rotor, a lock pin slidably provided within the receiving hole, an urging member for continuously urging the lock pin in one direction of its sliding directions, and a lock releasing oil passage that supplies hydraulic pressure for moving the lock pin in the other direction of its sliding directions against an urging force of the urging member. Such a lock mechanism is for restricting (locking) a relative rotation of both the rotors by urging the lock pin in the lock hole on the strength of an urging force of the urging member, as well as for releasing the lock of the relative rotation of both the rotors by releasing the engagement between the lock pin and the lock hole against an urging force of the urging member relaying upon hydraulic pressure applied from the lock-releasing oil passage.
In cases where the lock pin slides and the urging member urges radially to the valve timing adjusting device (hereinafter referred to simply as “radially to the device”), it is necessary by all costs to build in an locking member for preventing the urging member from coming off from the receiving hole at the outermost of the receiving hole formed radially to the device.
The structure of the locking member of a conventional valve timing adjusting device and a method of preventing the member from coming off are described in a variety of prior documents. For example, JP 10-339116 A discloses a method of preventing fallout of a locking member by closing the outermost part of the receiving hole formed radially to the device by an inner peripheral surface of a timing pulley constituting a part of the first rotor. However, such a method of preventing fallout of the locking member cannot not only be disadvantageously applied to a valve timing adjusting device, which does not include a timing pulley, but also be disadvantageously avoided dimensional expansion developing radially to the device in the outer part of the receiving hole out of sheer necessity of closing the receiving hole by the inner peripheral surface of the timing pulley.
Meanwhile, JP 11-101107 A discloses an locking member (plate-shaped retainer), which is engaged in a groove that extends axially to the device and opens to the end face located axially to the device. However, because sliding direction of the lock pin and inserting direction of the locking member cross each other at right angles, it must involve a process of temporarily compressing inwardly the urging member radially to the device by means of a jig when inserting the locking member therein, and of pulling out the jig therefrom after an insertion of the locking member is completed, with disadvantageously requires much time for assembly.
Moreover, WO01/34947A discloses a method of restricting the movement of an locking member, which is slidably provided in a receiving hole in a sliding direction of the lock pin by a restricting member inserted axially to the device. However, the addition of the restricting member is required as a new separate component for preventing fallout of the locking member, which disadvantageously incurs an increase in manufacturing cost.